Ultra-thin tubular graphitic carbon Nitride-Carbon Dot lateral heterostructures: One-Step synthesis and highly efficient catalytic hydrogen generation

Abstract

Lateral heterostructures (LHSs) consisting of two-dimensional (2D) layered materials are generally nanosheets that are unfavourable to various applications, such as photocatalysis, because they are prone to agglomerate and against for multiple absorption and utilization of light. Herein, for the first time, we prepare ultra-thin tubular LHSs of graphitic carbon nitride and carbon dots (CN/C-Dots), with thickness of ~8.0 nm via a facile, one-step thermal polymerization of the supramolecular complexes composed of melamine, cyanuric acid and β-cyclodextrin (β-CyD) as starting monomers. Interestingly, the structural topology of the CN/C-Dots LHSs can be effectively modulated by the amount of β-CyD. The obtained tubular porous LHSs are nearly perfect nanotubes with wall thickness of about 8.0 nm, the smallest one reported so far, which not only greatly increases the accessibility of active sites and light harvesting via high light absorption and scattering, but also shortens the route of carriers migrating towards the surface and improves the mass transport. In comparison with CN, the optimized ultra-thin tubular porous CN/C-Dots100 LHSs exhibit significantly boosted visible light photocatalytic hydrogen evolution activity (up to 113 times) of 24,760 μmol h−1 g−1 (λ > 420 nm), much higher than that over pure or nonmetal modified CN tubes reported to date. Moreover, the tubular porous CN/C-Dots100 LHSs are first demonstrated to be excellent electrocatalysts for hydrogen evolution reaction (HER) and oxgen evolution reaction (OER), achieving a geometrical catalytic current density of 10 mA cm−2 at overpotentials 415 and 340 mV in 0.5 M H2SO4 and 1 M KOH versus the reversible hydrogen electrode (RHE), respectively. These findings may provide insights into constructing highly efficient catalysts by tuning structural topology and heterojunction for different energy-related applications.